1. Field of the Invention
The present invention relates generally to communication systems, and pertains more particularly to a communication system suitable for use in an SV camera (electronic still video camera) or the like.
2. Description of the Related Art
To convert external AC power into DC power to be supplied as electric power, a conventional SV camera or the like has an arrangement such as that shown in FIG. 1. In the shown arrangement, a coupler 2 is fitted into a portion 54 for accommodating a dedicated battery 50 for a camera body 1 so that electrical power can be supplied thereto through electric contacts which are also available for supplying electrical power from the dedicated battery 50.
In the field of such an SV camera, there has also been a need for a wireless remote-control function or other similar means for externally controlling the SV camera.
In wireless remote control, it is necessary that a sensor for receiving infrared light from a wireless remote controller and a CPU for decoding received data be disposed somewhere in the system.
To meet the necessity, in general, a light receiving sensor 51 is disposed on the camera body 1 as shown in FIG. 1 and the CPU of the camera body 1 directly receives and decodes an output from the light receiving sensor 51. In FIG. 1, the light receiving sensor 51 can be detachably attached to the camera body 1, and elements 52 and 53 constitute a plug and socket.
In the above-described example, to enable the camera body 1 to receive a signal from the wireless remote controller, the power supply of the camera body 1 must be on at all times. As a result, even in a case where the SV camera has not been operated by the use of wireless remote control, it is impossible to utilize what is called automatic shut-off, i.e., the function of automatically shutting off the power supply. This is undesirable in that if a user forgets to turn off the power supply, more electric power will be consumed than is necessary.
In addition, the above-described conventional example has the following disadvantages:
(1) The size of the camera body becomes larger by the size of the light receiving sensor.
(2) The cost of the camera body increases.
(3) The current consumption of the camera body increases.
(4) Processing load applied to the CPU of the camera body increases.